US4841271A - Trip-free resetting mechanism for an on-off unit - Google Patents

Trip-free resetting mechanism for an on-off unit Download PDF

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Publication number
US4841271A
US4841271A US07/002,161 US216187A US4841271A US 4841271 A US4841271 A US 4841271A US 216187 A US216187 A US 216187A US 4841271 A US4841271 A US 4841271A
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United States
Prior art keywords
resetting
diaphragm
switch
lever
button
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US07/002,161
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English (en)
Inventor
Robert F. Purssell
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ranco Inc of Delaware
Original Assignee
Ranco Inc of Delaware
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ranco Inc of Delaware filed Critical Ranco Inc of Delaware
Assigned to RANCO INCORPORATED, A OHIO CORP. reassignment RANCO INCORPORATED, A OHIO CORP. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: PURSSELL, ROBERT F.
Assigned to RANCO INCORPORATED OF DELAWARE, AN OH CORP. reassignment RANCO INCORPORATED OF DELAWARE, AN OH CORP. MERGER (SEE DOCUMENT FOR DETAILS). EFFECTIVE DATE: DECEMBER 31, 1987, OHIO Assignors: RANCO INCORPORATED, AN OH CORP.
Application granted granted Critical
Publication of US4841271A publication Critical patent/US4841271A/en
Assigned to BANKERS TRUST COMPANY reassignment BANKERS TRUST COMPANY SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: RANCO INCORPORATED A CORP. OF DELAWARE
Assigned to RANCO INCORPORATED OF DELAWARE reassignment RANCO INCORPORATED OF DELAWARE CORRECTION OF RECORDED DOCUMENT TO CORRECT ADDRESS OF THE ASSIGNEE PREVIOUSLY RECORDED AT REEL 4926 FRAMES 923-927. (SEE RECORD FOR DETAILS) Assignors: RANCO INCORPORATED
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H35/00—Switches operated by change of a physical condition
    • H01H35/24—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow
    • H01H35/34—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow actuated by diaphragm
    • H01H35/343—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow actuated by diaphragm by snap acting diaphragm
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/64—Contacts
    • H01H37/70—Resetting means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/64—Contacts
    • H01H37/70—Resetting means
    • H01H2037/705—Resetting means wherein the switch cannot be closed when the temperature is above a certain value

Definitions

  • the present invention relates to trip-free mechanism for resetting on-off units of the type breakable by the tripping of an actuator element from a first condition to a second condition.
  • Such a mechanism is applicable particularly but not exclusively to an on-off unit constituted by a fail-safe remote sensing limit thermostat in which the actuator element comprises a flexible diaphragm supported by a housing and normally kept in an inwardly dished configuration relative to a closed chamber containing a fluid at sub-atmospheric pressure by the external atmospheric pressure, the fluid in the chamber expanding of vaporising at a predetermined limit temperature sensed by the thermostat so as to increase the pressure in the chamber and cause the diaphragm to snap into a stable outwardly dished configuration whereby the diaphragm opens, through a switch operating member, the normally closed contacts of an electrical switch having a fixed contact supported by the housing and a movable contact carried by a resiliently deflectable blade anchored relative to the housing, the blade normally biasing the movable contact into engagement with the fixed contact.
  • Thermostats of this type are used to protect electrical equipment and appliances from operating at excessive temperatures.
  • the object of the present invention is to provide a trip-free mechanism for resetting on-off units of the aforesaid type, which ensures that the unit remains in its broken condition during resetting and thus ensures that the unit can be re-made only when safe conditions exist.
  • the present invention provides a trip-free mechanism for resetting an on-off unit breakable by the tripping of an actuator element from a first condition to a second condition, the mechanism comprising a resetting member engageable to apply a resetting force to the actuator element to reset the latter in its first condition, and restraining means acted upon by the resetting member when it applies the resetting force to the actuator element to maintain the unit in its broken condition until the resetting member is disengaged upon resetting of the actuator element.
  • the resetting member comprises a push button which is pressed to apply a resetting force to the diaphragm through the switch operating member
  • the restraining member comprises a transmission element which, upon pressing of the button, holds the switch contacts open until the diaphragm is reset and the button released, the contacts then being closed by the resilience of the blade.
  • the push button may be operable manually or automatically.
  • the transmission element comprises a cranked lever pivoted on the housing at its elbow and having one end acted upon by the push button and acting at its other end on the movable switch contact, the said one end of the lever and the push button having complementary ramp surfaces which cooperate upon pressing of the button to cause the lever to pivot into an orientation in which its other end holds the contacts open.
  • the lever offers no resistance to the resilient return force of the blade.
  • levers may employ different transmission elements from the lever, for example a simple cam or gear system.
  • the resetting mechanism can be applied equally well to other types of on-off units, such as valves, circuit-breakers, thermostats with bimetallic actuators, and the like.
  • FIG. 1 is a diagrammatic sectional view of a fail-safe remote-sensing limit thermostat incorporating a trip-free resetting mechanism according to the invention, in a first operative condition;
  • FIG. 2 is a view similar to FIG. 1, showing the mechanism in a second operative condition
  • FIG. 3 is a cross sectional view seen approximately from the plane indicated by the line 3--3 of FIG. 1;
  • FIG. 4 is a cross-sectional view seen approximately from the plane indicated by the line 4--4 of FIG. 2.
  • a fail-safe remote-sensing limit thermostat 1 including a housing 2 and a resilient actuator diaphragm 3 hermetically sealed at its periphery to a casing 4 secured to the housing 2.
  • the diaphragm 3 and the casing 4 define a closed chamber 5 containing a fluid which is normally at sub-atmospheric pressure but is selected to vaporise at a predetermined limit temperature sensed at a location of an electrical appliance controlled by the thermostat 1 by a capillary tube 6 extending from the casing 4.
  • the thermostat 1 further includes an electrical switch comprising a fixed contact (FIGS. 3 and 4) supported by the housing 2 and connected to a respective terminal (FIGS. 3 and 4), a movable contact (not shown) carried by a resiliently deflectable blade 7 connected to a respective terminal (not shown) supported by the housing 2, and a switch operating member 8 between the diaphragm 3 and the blade 7.
  • an electrical switch comprising a fixed contact (FIGS. 3 and 4) supported by the housing 2 and connected to a respective terminal (FIGS. 3 and 4), a movable contact (not shown) carried by a resiliently deflectable blade 7 connected to a respective terminal (not shown) supported by the housing 2, and a switch operating member 8 between the diaphragm 3 and the blade 7.
  • the fluid pressure within the chamber 5 is below atmospheric pressure whereby the diaphragm 3 is kept in an inwardly-dished configuration relative to the chamber 5 (FIG. 2) and the contacts are closed by virtue of the resilience of the blade 7.
  • the limit temperature is reached at the location monitored (or if there is a leakage into the chamber 5 from the exterior)
  • the fluid pressure in the chamber 5 increases until the pressure difference across the diaphragm 3 is small enough for the diaphragm 3 to trip, that is, to snap overcentre against the atmospheric pressure by virtue of its own resilience.
  • the diaphragm 3 trips (FIG. 1) the motion is transmitted by the member 8 to the blade 7 and the contacts are opened to switch off the appliance.
  • the thermostat 1 is provided with a trip-free resetting mechanism according to the invention.
  • the resetting mechanism comprises a manually-operable reset button 9 which projects from the housing 2 and, when pressed, applies a resetting force to the diaphragm 3 through the member 8, and a cranked restraining lever 10 which is acted upon by the button 9 when it is pressed to hold the contacts open until the button 9 is released.
  • the lever 10 is pivoted on the housing 2 at its elbow 11 and is acted upon at one end 10A by the button 9 and acts at its other end 10B on the blade 7.
  • the end 10A of the lever 10 has a ramp surface complementary with a ramp surface formed on a lateral appendage 12 of the button 9.
  • the resetting mechanism is applicable equally well to single-pole single-throw (SPST) and single-pole double-throw (SPDT) versions of the thermostat.
  • the resetting mechanism of the invention as described above achieves "trip-freeness" by virtue of the fact that the contacts cannot close to re-start the appliance until the button 9 has been released after the resetting of the diaphragm 3: it is not possible to override the thermostat 1 by jamming the button 9 in. It depressed position, since this will only serve to keep the contacts open through the lever 10.

Landscapes

  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Thermally Actuated Switches (AREA)
  • Mechanical Control Devices (AREA)
  • Breakers (AREA)
US07/002,161 1986-01-17 1987-01-12 Trip-free resetting mechanism for an on-off unit Expired - Fee Related US4841271A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB08601115A GB2185629B (en) 1986-01-17 1986-01-17 Trip-free resetting machanism for an on-off unit
GB8601115 1986-01-17

Publications (1)

Publication Number Publication Date
US4841271A true US4841271A (en) 1989-06-20

Family

ID=10591536

Family Applications (1)

Application Number Title Priority Date Filing Date
US07/002,161 Expired - Fee Related US4841271A (en) 1986-01-17 1987-01-12 Trip-free resetting mechanism for an on-off unit

Country Status (6)

Country Link
US (1) US4841271A (da)
EP (1) EP0230748A3 (da)
DE (1) DE230748T1 (da)
DK (1) DK5187A (da)
GB (1) GB2185629B (da)
NO (1) NO870197L (da)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5790009A (en) * 1997-01-21 1998-08-04 Black & Decker Inc. Thermostat reset with additional electrical switch
US5854585A (en) * 1997-04-10 1998-12-29 Texas Instruments Incorporated Manual reset electrical equipment protector apparatus
US20050231318A1 (en) * 2004-04-15 2005-10-20 James Bullington Trip-free limit switch and reset mechanism
US20060082432A1 (en) * 2004-06-10 2006-04-20 Toshiharu Hayashi Manual-reset thermostat
US20060279397A1 (en) * 2005-06-08 2006-12-14 Derek Rose Trip-free manual reset thermostat
US20190187001A1 (en) * 2017-12-19 2019-06-20 E.G.O. Elektro-Geraetebau Gmbh Method for changing a working fluid in an expansion system, and expansion system
US11264197B2 (en) * 2020-02-27 2022-03-01 Air Distribution Technologies Ip, Llc Thermal sensor reset rod for thermal sensor
US11555623B2 (en) * 2020-02-27 2023-01-17 Air Distribution Technologies Ip, Llc Damper test switch fail-safe actuator

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5003282A (en) * 1989-07-19 1991-03-26 Texas Instruments Incorporated Trip free/reset free manual reset

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3081388A (en) * 1961-03-22 1963-03-12 Therm O Disc Inc Thermostatic controls
US3781744A (en) * 1972-06-27 1973-12-25 Honeywell Inc Manual reset for a switch device
US3924213A (en) * 1974-09-30 1975-12-02 Ranco Inc Thermostat
US4039991A (en) * 1975-12-18 1977-08-02 Elmwood Sensors, Inc. Thermostatic switch with reset mechanism
US4480246A (en) * 1982-10-18 1984-10-30 Therm-O-Disc, Incorporated Trip-free manual reset thermostat

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB945950A (en) * 1960-03-17 1964-01-08 Claus Holmer Gerdes A thermally responsive electric switch
US3219783A (en) * 1963-07-12 1965-11-23 Therm O Disc Inc Manual reset thermostatic control
DE2605465A1 (de) * 1976-02-12 1977-08-18 Emerson Electric Gmbh Elektrischer schalter mit thermischer sicherheitsausloesung und von hand betaetigtem rueckstellmechanismus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3081388A (en) * 1961-03-22 1963-03-12 Therm O Disc Inc Thermostatic controls
US3781744A (en) * 1972-06-27 1973-12-25 Honeywell Inc Manual reset for a switch device
US3924213A (en) * 1974-09-30 1975-12-02 Ranco Inc Thermostat
US4039991A (en) * 1975-12-18 1977-08-02 Elmwood Sensors, Inc. Thermostatic switch with reset mechanism
US4480246A (en) * 1982-10-18 1984-10-30 Therm-O-Disc, Incorporated Trip-free manual reset thermostat

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5790009A (en) * 1997-01-21 1998-08-04 Black & Decker Inc. Thermostat reset with additional electrical switch
US5854585A (en) * 1997-04-10 1998-12-29 Texas Instruments Incorporated Manual reset electrical equipment protector apparatus
US20050231318A1 (en) * 2004-04-15 2005-10-20 James Bullington Trip-free limit switch and reset mechanism
US20060082432A1 (en) * 2004-06-10 2006-04-20 Toshiharu Hayashi Manual-reset thermostat
US7218200B2 (en) * 2004-06-10 2007-05-15 Wako Electronics Co., Ltd. Manual-reset thermostat
US20060279397A1 (en) * 2005-06-08 2006-12-14 Derek Rose Trip-free manual reset thermostat
US7479868B2 (en) 2005-06-08 2009-01-20 Therm-O-Disc, Incorporated Trip-free manual reset thermostat
US20190187001A1 (en) * 2017-12-19 2019-06-20 E.G.O. Elektro-Geraetebau Gmbh Method for changing a working fluid in an expansion system, and expansion system
US11761822B2 (en) * 2017-12-19 2023-09-19 E.G.O. Elektro-Geraetebau Gmbh Method for changing a working fluid in an expansion system, and expansion system
US11264197B2 (en) * 2020-02-27 2022-03-01 Air Distribution Technologies Ip, Llc Thermal sensor reset rod for thermal sensor
US11555623B2 (en) * 2020-02-27 2023-01-17 Air Distribution Technologies Ip, Llc Damper test switch fail-safe actuator

Also Published As

Publication number Publication date
NO870197L (no) 1987-07-20
NO870197D0 (no) 1987-01-16
EP0230748A2 (en) 1987-08-05
EP0230748A3 (en) 1989-06-14
DE230748T1 (de) 1988-04-28
DK5187A (da) 1987-07-18
GB2185629A (en) 1987-07-22
DK5187D0 (da) 1987-01-06
GB2185629B (en) 1989-01-25
GB8601115D0 (en) 1986-02-19

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AS Assignment

Owner name: RANCO INCORPORATED, 555 METRO PLACE NORTH, SUITE 5

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:PURSSELL, ROBERT F.;REEL/FRAME:004835/0189

Effective date: 19880129

Owner name: RANCO INCORPORATED, A OHIO CORP., OHIO

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:PURSSELL, ROBERT F.;REEL/FRAME:004835/0189

Effective date: 19880129

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Owner name: RANCO INCORPORATED OF DELAWARE, AN OH CORP.

Free format text: MERGER;ASSIGNOR:RANCO INCORPORATED, AN OH CORP.;REEL/FRAME:004926/0923

Effective date: 19880714

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Effective date: 19900730

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Owner name: RANCO INCORPORATED OF DELAWARE, DELAWARE

Free format text: CORRECTION OF RECORDED DOCUMENT TO CORRECT ADDRESS OF THE ASSIGNEE PREVIOUSLY RECORDED AT REEL 4926 FRAMES 923-927.;ASSIGNOR:RANCO INCORPORATED;REEL/FRAME:006605/0578

Effective date: 19930310

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Effective date: 19970625

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Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362